Not crying

Ok this might be silly but I get worried. Our almost 4 month old sleeps in his own room and in his crib. We have a video monitor on him. He sleeps amazing!!!! The issue is when he does wake up he doesn't have a set schedule he's just so little still that he won't cry. So when I am sleeping I don't know he's awake. He is just so content in his crib. When I do eventually hear him angry babble to himself he is so angry lol. When I pick him up he just gets so frustrated he wants to naw on any part of me. I feel terrible because there is no way to judge how long he has been awake. He just loves his crib so much he rather lay there quietly then cry. For the record this baby can cry and very loudly all other times of the day lol. Anyone else's baby similar? Picture of happy baby waking up in his crib.